Variable-contour compaction press

ABSTRACT

In a 3D-printing system, a deposition head comprising a band assembly having a body and a band for compacting a filament onto the surface of an object being manufactured. One or more actuators are mounted on the assembly body at a front mounting point or a rear mounting point, or both, and are used to shape the band to a desired contour. The band is made of a flexible material, and has a first and second connecting point, wherein at least one of them is connected to the one or more actuators. The intermediate portion of the band between the connecting points is curved toward the surface of the object being manufactured to enable the portion to come into contact with and to compact the filament onto the object. The band assembly further comprises a compaction support extending from the assembly body toward an inward-facing surface of the band.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to “Variable-Contour Compaction Roller,”application Ser. No. 15/959,214, and “Self-Cleaning Variable-ContourCompaction Press,” application Ser. No. 15/959,215, both of which areincorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to additive manufacturing ofthree-dimensional objects in general, and, more particularly, to adeposition head featuring a band for compacting a filament onto asurface of an object being manufactured.

BACKGROUND

In general, there are two complementary approaches to manufacturing anobject: additive manufacturing and subtractive manufacturing.

Additive manufacturing involves aggregating material to form the desiredobject. In contrast, subtractive manufacturing involves removingmaterial to form the desired object. In practice, many objects aremanufactured using a combination of additive and subtractive techniques.

A form of additive manufacturing—colloquially known as“three-dimensional (3D) printing”—is the subject of intense research anddevelopment because it enables objects with complex geometries to bemanufactured without molds or dies. Furthermore, 3D printing enables themass customization of objects with different dimensions andcharacteristics.

In at least one 3D printing technique, the object is built by providinga thermoplastic filament to a deposition head on a robotic arm. Thethermoplastic filament comprises a continuous tow of carbon fibers thatis impregnated with thermoplastic. The deposition head heats anddeposits the thermoplastic filament as one or more runs of material, viaa roller. After it is deposited, each run quickly solidifies and fuseswith the runs that it touches. The technique builds a three-dimensionalobject from a mathematical model of the object.

FIG. 1 in the prior art depicts an illustration of the components ofadditive manufacturing system 100, which uses a thermoplastic filamentas described above. Additive manufacturing system 100 comprises:controller 101, build chamber 102, turntable 110, deposition platform111, robot 121, deposition head 122, filament source 130, andthermoplastic filament 131. Manufacturing system 100 is used tomanufacture object 151.

Controller 101 comprises the hardware and software necessary to directbuild chamber 102, robot 121, deposition head 122, and turntable 110, inorder to manufacture object 151. The controller also directs at leastsome of the components that are part of deposition head 122. Controller101 comprises computer-aided design/computer-aided manufacturing(CAD/CAM) functionality in order to control the aforementionedcomponents.

Build chamber 102 is a thermally-insulated, temperature-controlledenvironment in which object 151 is manufactured.

Turntable 110 comprises a stepper motor under the control of controller101 that is capable of rotating platform 111 (and, consequently object151) around an axis of rotation.

Platform 111 comprises hardware on which object 151 is manufactured.Platform 111 is configured to receive heated filament deposited bydeposition head 122. In some embodiments, platform 111 is referred to asa “build plate.”

Robot 121 is capable of depositing a run of material from anythree-dimensional coordinate in build chamber 102 to any otherthree-dimensional coordinate in build chamber 102 with deposition head122 at any approach angle. To this end, robot 121 comprises amulti-axis, mechanical arm under the control of controller 101.

Deposition head 122 comprises hardware that is under the control ofcontroller 101 and that deposits filament 131, which may partially orwholly contain one or more fiber strands.

Thermoplastic filament 131 comprises a cylindrical towpreg of continuous12K carbon fiber that is impregnated with a thermoplastic and issupplied from filament source 130. Filament 131 is deposited as a “runof material” onto object 151 or platform 111, or both.

FIG. 2 in the prior art depicts a schematic representation of thespatial relationship of deposition head 122 to segments of thermoplasticfilament 131, including previously deposited segments of filament thatmake up object 151. Deposition head 122 comprises: roller 201, rolleraxle 202, roller guide 203, and filament guide 204, and a laser (notshown). Roller 201, roller axle 202, roller guide 203, filament guide204, and the laser are held in relative position by a support structurethat is not shown in FIG. 2.

Roller 201 is a metal wheel with roller bearings on roller axle 202 thatis positioned by roller guide 203. Roller 201 rotates freely on rolleraxle 202 and presses filament 131, heated by the laser, into previouslydeposited filament of object 151. Filament 131 is pressed into thepreviously deposited filament to facilitate adhesion and eliminatevoids.

Filament guide 204 guides filament 131 into position so that roller 201can press it into the previously deposited filament. At least a portionof filament guide 204 is transparent to the light from the laser so thatthe laser can add heat to filament 131 while filament 131 is withinfilament guide 204.

Where the surface of object 151 is flat, or convex, or even slightlyconcave, the contour of the surface does not impede roller 201 in itsability to press filament 131, as depicted in FIG. 2. However, where thesurface of object 151 is excessively concave, the surface concavitiescan impede roller 201's ability to press filament 131 into the objectbeing manufactured. In particular, where the compaction roller has toolarge a diameter to follow the contour of a concavity, the roller mightbe unable to properly press the filament into position. The roller mightalso be unable to properly press the filament into position if a wall ofa concavity is sloped in a direction that is inconsistent with thedirection of travel of deposition head 122, even if the concavity is notexcessively concave in relation to the roller's diameter.

What is needed is a system for applying filament to an object beingmanufactured, without at least some of the disadvantages in the priorart.

SUMMARY OF THE DISCLOSURE

In at least one 3D-printing technique, a deposition head depositsthermoplastic filament on an object being manufactured and presses thefilament in place with a compaction roller directly in contact with thefilament. Where the surface of the object is excessively concave orsloped in a direction inconsistent with the deposition head's directionof travel, the surface's contours can impede the roller's ability topress the filament into position. One such scenario is where thecompaction roller has too large a diameter to follow the contour of aconcavity. A solution to this scenario might be to use a compactionroller having a smaller diameter to follow the contour of a concavity; asmaller roller, however, would be impractical to use across the overallobject being manufactured.

The present invention enables the deposition of thermoplastic filamentonto an object whose surface has one or more concavities, without atleast some of the disadvantages in the prior art. In accordance with theillustrative embodiment of the present invention, a deposition headcomprises an assembly having an assembly body and a band for compactinga filament onto the surface of the object. One or more actuators aremounted on the assembly body at a front mounting point or a rearmounting point, or both, and are used to shape the band to a desiredcontour.

The band is made of a flexible material, and has a first and secondconnecting point, wherein at least one of them is connected to the oneor more actuators. The intermediate portion of the band between thefirst and second connecting points is curved toward the surface of theobject being manufactured to enable the portion of the band to come intocontact with and to compact the filament onto the object beingmanufactured.

The band assembly further comprises a compaction support extending fromthe assembly body toward an inward-facing surface of the band. Thecompaction support is configured to support the band at the point ofcompaction.

In accordance with the illustrative embodiment, each actuator is capableof imparting a mechanical motion to the band. For example, an actuatormounted at the rear mounting point on the assembly body can beconfigured to impart, at the connecting point on the band, a rotationalmotion, a linear lateral motion, a linear longitudinal motion, or alinear vertical motion. Additional actuators can be used at theconnecting point on the band to impart compound motion to the band, andone or more actuators can be used at the front of the band, in additionto the rear, in order to achieve additional types of motion at theconnecting points.

By moving one or both connecting points on the band using the actuators,the band itself can assume different shapes and, in particular,different contours at or near the point of compaction of the filamentbeing deposited. Advantageously, the contour of the band can be varied,by a controller, in order to match the changing contours of the surfaceof the object being manufactured, thereby improving the deposition andcompaction of the filament by the band acting as a press.

In some embodiments of the present invention, although the band can bemoved at its connecting points with the actuators, the band is fixed interms of any motion along its length. Having a band that is fixed interms of such motion, or limited in this motion, enables the band to beused as a plow, which can be advantageous in certain applications. Insome other embodiments of the present invention, the band is capable ofmotion along its length.

An illustrative deposition head for pressing a filament at a point ofcompaction on a surface of an article of manufacture comprises: afilament drive that is configured to feed the filament toward the pointof compaction; a heat source that is configured to heat the filament asit passes through an area between the filament drive and the point ofcompaction; a body having a front mounting point and a rear mountingpoint that are arranged along a longitudinal axis; a first actuator thatis connected to the rear mounting point; and a band made of a flexiblematerial, and having a first connecting point that is connected to thefront mounting point and a second connecting point that is connected tothe rear mounting point through the first actuator, such that anintermediate portion of the band between the first connecting point andsecond connecting point is curved toward the surface of the article;wherein the first actuator is configured to impart a mechanical motionat the second connecting point of the band, in relation to the rearmounting point, such that the band conforms, at the point of compaction,to at least some concavities in the surface of the article.

Another illustrative deposition head for pressing a filament at a pointof compaction on a surface of an article of manufacture comprises: abody having a front mounting point and a rear mounting point arrangedalong a longitudinal axis; a first actuator that is connected to thebody at one of the front mounting point and the rear mounting point, aband made of a flexible material, and having a first connecting pointthat is connected to the front mounting point and a second connectingpoint that is connected to the rear mounting point, wherein one of thefirst connecting point and second connecting point is connected to therespective first or second mounting point through the first actuator,such that an intermediate portion of the band between the firstconnecting point and second connecting point is curved toward thesurface of the article; and a first compaction support extending fromthe body toward an inward-facing surface of the band, and configured tosupport the band at the point of compaction; wherein the first actuatoris configured to impart a first mechanical motion to one of the firstconnecting point and the second connecting point of the band, inrelation to the body.

Yet another deposition head for pressing a filament at a point ofcompaction on a surface of an article of manufacture comprises: a bodyhaving a front mounting point and a rear mounting point arranged along alongitudinal axis; a first actuator that is connected to the body at oneof the front mounting point and the rear mounting point, a secondactuator that is connected to the body at one of the front mountingpoint and the rear mounting point, and a band made of a flexiblematerial, and having a first connecting point that is connected to thefront mounting point and a second connecting point that is connected tothe rear mounting point, wherein one of the first connecting point andsecond connecting point is connected to the respective first or secondmounting point through the first actuator, such that an intermediateportion of the band between the first connecting point and secondconnecting point is curved toward the surface of the article; whereinthe first actuator is configured to impart a first mechanical motion toone of the first connecting point and the second connecting point of theband, in relation to the body; and wherein the second actuator isconfigured to impart a second mechanical motion to one of the firstconnecting point and the second connecting point of the band, inrelation to the body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 in the prior art depicts an illustration of the components ofadditive manufacturing system 100.

FIG. 2 in the prior art depicts a representation of the spatialrelationship of deposition head 122 to a segment of thermoplasticfilament 131.

FIG. 3 depicts a front-view illustration of the salient components ofadditive manufacturing system 300 in accordance with the illustrativeembodiment of the present invention.

FIG. 4 depicts an orthographic front view illustration of depositionhead 322.

FIGS. 5A and 5B depict an orthographic front-view illustration andleft-side-view illustration, respectively, of some of the components ofdeposition head 322 that interact with band 402

FIG. 6 depicts an orthographic front view of a configuration in whichtwo compaction supports are present, including a second compactionsupport 601 connected to second compaction roller 602.

FIGS. 7A and 7B depict an orthographic front-view illustration andleft-side-view illustration, respectively, of rear actuator 505.

FIGS. 8A and 8B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401, with actuators502 and 505 in their neutral positions.

FIGS. 9A and 9B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401, depictinglinear longitudinal motion.

FIGS. 10A and 10B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401, depictinglinear lateral motion.

FIGS. 11A and 11B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401, depictinglinear vertical motion.

FIGS. 12A and 12B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401, depictingrotational motion.

FIG. 13 depicts salient operations of method 1300 according to theillustrative embodiment.

FIG. 14 depicts operation 1309 for advancing band 402 along its length.

DETAILED DESCRIPTION

For the purposes of this specification, the following terms and theirinflected forms are defined as follows:

-   -   The term “band” is defined as a strip or loop of material.    -   The term “vertical” is defined as at right angles to a        horizontal plane.    -   The term “lateral” is defined as sideways.    -   The term “longitudinal” is defined as running lengthwise        (front-to-back) rather than across.    -   The term “convex” is defined as having an outline or a surface        that is curved or rounded outward.    -   The term “concave” is defined as having an outline or a surface        that is hollowed or rounded inward.    -   The term “contour” is defined as an outline, especially one        representing or bounding the shape or form of something.    -   The term “to conform” is defined to mean “to be similar in form        or type.”

The deposition head of the illustrative embodiment is described in thisspecification in the context of a band that presses thermoplasticfilament onto an object being manufactured in an additive manufacturingsystem. As those who are skilled in the art will appreciate, however,after reading this specification, the disclosed deposition head can beused in various other applications, and with either filaments or otherslender threadlike objects or fibers.

FIG. 3 depicts a front-view illustration of the salient components ofadditive manufacturing system 300 in accordance with the illustrativeembodiment of the present invention. Additive manufacturing system 300comprises: controller 301, build chamber 302, turntable 310, depositionplatform 311, robot 321, deposition head 322, filament source 330, andthermoplastic filament 331. A purpose of manufacturing system 300 is tomanufacture object 351, which is an article of manufacture or anapparatus.

Controller 301 comprises the hardware and software necessary to directbuild chamber 302, robot 321, deposition head 322, and turntable 310, inorder to manufacture object 351. The controller also directs at leastsome of the components that are part of deposition head 322, asdescribed below. Controller 301 comprises computer-aideddesign/computer-aided manufacturing (CAD/CAM) functionality in order tocontrol the aforementioned components. It will be clear to those skilledin the art, after reading this disclosure, how to make and usecontroller 301.

Build chamber 302 is a thermally-insulated, temperature-controlledenvironment in which object 351 is manufactured. It will be clear tothose skilled in art how to make and use build chamber 302.

Turntable 310 comprises a stepper motor under the control of controller301 that is capable of rotating platform 311 (and, consequently object351) around an axis of rotation. In particular, turntable 310 is capableof:

-   -   i. rotating platform 311 clockwise around the axis of rotation        from any angle to any angle, and    -   ii. rotating platform 311 counter-clockwise around the axis of        rotation from any angle to any angle, and    -   iii. rotating platform 311 at any rate, and    -   iv. maintaining (statically) the position of platform 311 at any        angle.

In some embodiments of the present invention, turntable 310 is furthercapable of being positioned in general (i.e., not being limited torotation around the aforementioned axis), under the control ofcontroller 301, and accordingly is sometimes referred to as a “buildplate positioner.” It will be clear to those skilled in the art how tomake and use turntable 310.

Platform 311 comprises hardware on which object 351 is manufactured.Platform 311 is configured to receive heated filament deposited bydeposition head 322. In some embodiments, platform 311 is referred to asa “build plate.”

As those who are skilled in the art will appreciate, platform 311 neednot be coupled to a turntable, in order for it to receive the heatedfilament. In any event, it will be clear to those skilled in the art howto make and use platform 311.

Robot 321 is capable of depositing a run of material from anythree-dimensional coordinate in build chamber 302 to any otherthree-dimensional coordinate in build chamber 302 with deposition head322 at any approach angle. To this end, robot 321 comprises a multi-axis(e.g., six-axis, seven-axis, etc.), mechanical arm under the control ofcontroller 301. A non-limiting example of robot 321 is the IRB 4600robot offered by ABB. It will be clear to those skilled in the art howto make and use robot 321.

Deposition head 322 comprises hardware that is under the control ofcontroller 301 and that deposits filament 331, which may partially orwholly contain one or more fiber strands. Deposition head 322 isdescribed below and in regard to FIG. 4. Deposition head 322 is anexample of an “end effector” in relation to robot 321, being attached torobot 321 at the robot's wrist.

Thermoplastic filament 331 comprises a cylindrical towpreg of continuous12K carbon fiber that is impregnated with a thermoplastic and issupplied from filament source 330 (e.g., a spool, etc.). In somealternative embodiments, filament 331 is impregnated with somethingother than, or in addition to, a thermoplastic. It will be clear tothose skilled in the art, after reading this disclosure, how to make anduse alternative embodiments of the present invention in whichthermoplastic filament 331 has a different fiber composition, such asone described in U.S. patent application Ser. No. 14/184,010, which isincorporated by reference herein.

Thermoplastic filament 331 is deposited as a “run of material” ontoobject 351 or platform 311, or both. For purposes of clarity, filament331 is depicted in FIG. 3 as being separate from object 351. Theparticular shape of object 351 as depicted has been selected forpedagogical purposes; however, additive manufacturing system 300 iscapable of building any of a variety of objects.

FIG. 4 depicts an orthographic front view illustration of depositionhead 322. Deposition head 322 comprises: deposition head mount 400, bandassembly 401 that includes band 402 and band assembly body 404, filamentguide 405, filament guide support 406, heat source 407, heat sourcesupport 408, filament drive 409, and cutter 411, interconnected asshown. As those who are skilled in the art will appreciate after readingthis specification, one or more of the elements that are depicted asbeing part of deposition head 322 can instead be part of robot 321 or adifferent part of additive manufacturing system 300.

In regard to deposition head 322, the various terms that are used todescribe direction, including “vertical”, “horizontal”, “lateral”,“longitudinal”, “downward”, and “upward”, are defined with respect todeposition head 322 and band assembly 401, unless otherwise specified.For example, if the bottom of deposition head 322—and, by association,the bottom of band assembly 401—is rotated forward with respect to thebase of robot 321, then the upward direction of band assembly 401 iscorrespondingly rotated backward as a result.

Mount 400 of deposition head 322 comprises one or parts that areconfigured to mount the other components of deposition head 322 to thearm of robot 321.

Band assembly 401 comprises band 402, band assembly body 404, andadditional components that are configured to operate in accordance withthe illustrative embodiment, as described below and in regard to FIGS.5A and 5B.

Filament guide 405 is configured to guide filament 331 provided byfilament source 330, toward the deposition surface. Filament guide 405comprises a plate through which filament 331 can be heated. The filamentguide is attached to mount 400 via support 406. The details of filamentguide 405 are taught in co-pending U.S. patent application Ser. No.15/827,721, entitled “Filament Guide,” filed on Nov. 30, 2017, which isincorporated by reference for the purposes of disclosing how it is madeand used in conjunction with the deposition of heated filaments ofthermoplastic.

In some embodiments of the present invention, filament guide 405 isfluidically coupled to a conduit, which is configured to provide a gasfrom a source of the gas to filament guide 405, in particular tofilament 331 within guide 405. In some embodiments of the presentinvention, the gas that is used has properties enabling it to displaceoxygen such that combustion is inhibited when filament 331 is heated byheat source 407. For example and without limitation, the gas can benitrogen.

Heat source 407 is a heating device configured to heat filament 331while the filament is moving through guide 405. Heat source 407comprises a laser, configured to emit electromagnetic radiation in theform of infrared light. In some alternative embodiments of the presentinvention, the laser emits electromagnetic radiation in a differentform, while in some other embodiments heat source 407 uses a heat sourceother than a laser, or emits thermal energy that which might be in aform other than electromagnetic radiation, or both. In some embodimentsof the presenting invention, the laser in heat source 407 can be aLaserline LDM-800 diode laser that heats both a portion of a segment offilament 331 and a portion of a segment of previously-deposited filament351 under the control of controller 301. It will be clear to thoseskilled in the art, after reading this disclosure, how to makealternative embodiments of the present invention that use a differentlaser.

The particular source of the heat is sufficient to heat thethermoplastic in a portion of filament 331 prior to the portion reachingthe point of compaction on the deposition surface. When heated in thisway by heat source 407, the thermoplastic in the filament becomespliable and adhesive, and can be pressed and deposited by band 402. Theheat source is configured to produce a temperature at filament 331 thatis high enough to make the thermoplastic pliable and adhesive, but nottoo high. If the thermoplastic is too cool, it is not sufficientlypliable or adhesive, and if the thermoplastic is too hot, it melts andits viscosity becomes too low. When filament 331 is moving continuously,heat source 407 heats a continuum of affected portions of the filament.

Heat source 407, including the laser, is controlled by controller 301.The heat source is attached to mount 400 via support 408.

Filament drive 409 is configured to feed filament 331 at a feed velocitycontrolled by controller 301. Drive 409 feeds the filament forward, inparticular toward and through filament guide 405 toward the point ofcompaction. In some embodiments of the present invention, the feedvelocity is important in regard to design considerations of the drivemechanism of band 402. In some embodiments of the present invention,drive 409 is attached to mount 400 via its own support member.

Cutter 411 comprises a cutting mechanism that is configured to cutfilament 331, as needed and under the control of controller 301. Thecutting mechanism is constructed and arranged to cut filament 331 at alocation at or near, or upstream from, filament guide 405.

FIGS. 5A and 5B depict an orthographic front-view illustration andleft-side-view illustration, respectively, of some of the components ofdeposition head 322 that interact with band 402 of band assembly 401, indepositing and compacting filament 331. For clarity purposes, onlyportions of filament 331 that enter cutter 411 and filament guide 405,and that leave filament guide 405, are depicted.

Band assembly 401 comprises band 402, band assembly body 404, actuator502, actuator 505, lower band roller 508, compaction support 507, upperband roller 509, and spring assembly 510, interconnected as shown. Bandassembly body 404 has a front end and a rear end along a longitudinalaxis, and has a front mounting point 501 that disposed toward the frontend and a rear mounting point 504 that is disposed toward the rear end,to which actuator 502 and actuator 505 are respectively connected.Mounting points 501 and 504 are arranged along the longitudinal axis ofbody 404. As seen from behind deposition head 322, band assembly body404 is C-shaped, having a top, left, and bottom region; as those who areskilled in the art will appreciate after reading this specification,however, body 404 can be a different shape in some alternativeembodiments of the present invention.

Band 402 is a flat, thin loop of flexible material. As depicted in FIG.5A, band 402 is in the form of a loop having a circumference and ashape. In some alternative embodiments of the present invention, band402 is in the form of a strip curved downward toward object 351. Band402 has an inward-facing surface, which faces lower band roller 508 andcompaction support 507, and an outward-facing surface, which facesfilament 331 during deposition of the filament.

In order to deposit filament 331, band 402, as supported by compactionsupport 507 and band assembly body 404, is configured to apply apressing force between i) filament 331, when heated by heat source 407,and ii) deposition surface 521 at point of compaction 522. Depositionsurface 521 can be a surface of platform 311 or a surface of object 351.The pressing force is generated via the arm of robot 321 beingcontrolled by controller 301, and transferring the force through body404 and compaction support 507 to band 402 at the point of compaction.For the purposes of this specification, point of compaction 522, bydefinition, is always “under” the band at the point of compaction, asopposed to being at a fixed point or area on platform 311 or object 351.

Band 402 is capable of holding a defined shape for a predeterminedlength of time, based on one or more supports propping it up, asdescribed below. The defined shape enables band 402 to conform to thesurface of object 351. Furthermore, band 402 is capable of changing itsshape to other defined shapes and is capable of doing so repeatedly. Inorder to meet these requirements, band 402 is made of a material withsuitable fatigue characteristics—in particular, a material having a veryhigh fatigue limit (i.e., the stress below which the material does notfatigue). To this end, band 402 is made of tempered AISI 1095 steelbecause of its suitable fatigue characteristics. In some alternativeembodiments of the present invention, band 402 is made of a differentmaterial, but one still having suitable fatigue characteristics. Thesurface of band 402 should be as smooth as possible to reduce fouling(i.e., from the thermoplastic in filament 331) and can be coated withTeflon™ or some other suitable substance to reduce friction load.

The thickness of band 402 is determined by the stress imposed on theband, in terms of load attributed to the bending of the band (asdescribed above) and, to a lesser extent, load attributed to friction(e.g., shoe friction). In regard to its thickness, band 402 has auniform thickness on the order of 0.002″ to 0.003″ when used inconjunction with lower band roller 508 as described below. In someembodiments of the present invention, band 402 has a differentthickness. For example and without limitation, for a band that advancesrelatively slowly relative to the motion of robot 321 (e.g., when theband is being used as a plow or a press rather than as a roller), band402 can have a greater thickness such as 0.010″.

In regard to its width, band 402 has a width that is dependent, at leastin part, on the uncompacted diameter of filament 331 or on the compacteddiameter of filament 331, or both. For example and without limitation,with an uncompacted diameter of 1.2 mm and a compacted diameter of 3.0mm, the width of band 402 can be uniform and on the order of 5 mm to 8mm. In some embodiments of the present invention, band 402 has adifferent width or one that is dependent on other factors. In someembodiments, the width of band 402 can be dependent on the number offilaments being concurrently deposited; for example, the greater thenumber of filament, the greater the width. In some embodiments, thewidth of band 402 can be dependent on the type of material beingdeposited; for example, if tape is used instead of filament, the widthof band 402 might be greater.

In regard to band 402 having a configuration as a loop, the weld line inthe loop possibly introduces a failure point of the band itself. Inorder to prevent such a failure, the circumference of band 402 as a loopis made longer than the longest deposited segment of filament, and band402 is rewound or repositioned by controller 301 frequently enough notto have the weld line come in contact with the filament. In some otherembodiments of the present invention, controller 301 reduces the load onloop 402 as the weld line passes over the filament being deposited. Instill some other embodiments of the present invention, band 402 isconfigured as a strip, instead of as a loop, in which the strip ismaintained on two spools that are part of band assembly 401 (i.e., afront and rear spool); in this configuration, controller 301 rewindsstrip 402 before the strip gets to its end.

As those who are skilled in the art will appreciate after reading thisspecification, characteristics of band 402 that are different from thosedescribed above other are possible in alternative embodiments of thepresent invention. For example and without limitation, the material ofband 402 can vary (i.e., can be non-homogenous), the thickness of theband can be nonuniform, and the width of at least a portion of the bandcan be nonuniform (e.g., a concave edge, a convex edge, etc.).

In regard to the size of roller 508, the diameter of the roller isdependent, at least in part, on the thickness of band 402. Given theband thickness described above, the diameter of roller 508 can be 20 mmto 25 mm in some embodiments. In accordance with the illustrativeembodiment, the diameter of roller 508 is directly proportional to thethickness of band 402.

The width of roller 508 is dependent, at least in part, on the width ofband 402. Given the band width described above, the width of roller 508can be 10 mm to 15 mm in some embodiments. In accordance with theillustrative embodiment, the width of roller 508 is directlyproportional to the width of band 402. In some embodiments, a widerroller 508 can be better for compaction in surfaces with a single axisof curvature, while a narrower roller 508 can be better for compactionin surfaces with two axes of curvature.

Compaction support 507 extends from body 404 downward toward theinward-facing surface band 402 and is configured to support the band at(or near) point of compaction 522. In accordance with the illustrativeembodiment, support 507 is connected to compaction roller 508, which ismovably (e.g., rotatably, etc.) coupled to a vertical member of support507 and is permitted to roll as band 402 moves. Roller 508 is alsopermitted to move, as needed, with additional degrees of freedom,depending on the movement of band 402. In some alternative embodimentsof the present invention, support 507 has a different type of end than aroller (e.g., a shoe having a fixed shape to apply pressure to band 402according to a predefined distribution of force over a compaction area,etc.).

In some embodiments of the present invention, deposition head 322comprises more than one compaction support. FIG. 6 depicts anorthographic front view of a configuration in which two compactionsupports are present, including a second compaction support 601connected to second compaction roller 602. Also depicted is thirdcompaction support 603 connected to compaction shoe 604. As those whoare skilled in art will appreciate, after reading this specification, adifferent number of compaction supports can be present than depicted inFIGS. 5 and 6, with or without compaction rollers and/or shoes.Furthermore, different combinations of compaction rollers and compactionshoes can be present (e.g., one roller with no shoe, one roller with oneshoe, two rollers with no shoe, two rollers with one shoe, no rollerswith one shoe, no rollers with two shoes, etc.). The use of more thanone compaction support can be used to extend the contact area of band402 with surface 521, for example and without limitation; high-speeddeposition, for example, can benefit from extending the contact area inthe aforementioned way.

Each actuator 502 and 505 is a component of a machine that isresponsible for moving and controlling a mechanism or system—in thiscase the position of one or more points on band 402 and, as a result,the shape of the band with respect to surface 521. Each actuatorutilizes control signals from controller 301 and a source of energy forturning a drive motor for rotational motion, moving a solenoid forlinear motion, etc. As those who are skilled art will appreciate afterreading this specification, band assembly 401 can have, in somealternative embodiments of the present invention, an actuator in thefront only or an actuator in the rear only, in which cases band 402 isconnected at its connecting point to mounting point on body throughdifferent means than the actuator. Actuators 502 and 505 are describedbelow and in FIGS. 7A and 7B.

Band 402 is capable of a variety of configurations in relation tomounting points 501 and 504, or actuators 502 and 505, or both. In afirst variation of the illustrative embodiment, in which band 402 isfixed, at least at certain times, band 402 has a connecting point 503that is connected to front mounting point 501 through actuator 502 and aconnecting point 506 that is connected to rear mounting point 504through actuator 505. In this first variation, band 402 is connected tosaid elements in such a way that an intermediate portion of band 402between connecting points 503 and 506 on the band is curved toward thesurface 521.

In a second variation of the illustrative embodiment, in which band 402is moveable, at least at certain times, band 402 is arranged in such away that the front of the band (e.g., a loop, a strip, etc.) and a frontwheel are in contact with each other at point of contact 503, the backof the band and a rear wheel are in contact with each other at point ofcontact 506, and the bottom of band 402 faces downward toward surface521. For example, FIGS. 7A and 7B depict an orthographic front-viewillustration and left-side-view illustration, respectively, of rearactuator 505 comprising lower member 701, upper member 702, and rearwheels 703 and 704. Band 402 is seen as traversing members 701 and 702(internally, depicted as dashed lines), and is in contact with at leastone of rear wheels 703 and 704 (internal to member 701 and depicted asdashed lines) at point of contact 506.

Similarly, front actuator 502 comprises a lower and upper member(depicted in subsequent drawings as members 705 and 706, respectively),and at least one front wheel; band 402 traverses the members of thefront actuator and is in contact with at least one of the front wheelsat point of contact 503. Although actuator 502 is not depicted, actuator505 as depicted in FIGS. 7A and 7B and as described herein isrepresentative of any actuator in contact with band 402.

In addition to actuator-related components that are well-known in theart, members 701, 702, 705, and 706 also comprise any components relatedto guiding and stabilizing band 402 as it passes through each member.

In some embodiments of the present invention, components 502 and/or 505can comprise multiple actuators for multiple movements, as depicted insubsequent drawings. Each actuator is configured to receive and respondto control signals from controller 301 in order to control each type ofmechanical motion, such that a portion of the band conforms to the pointof compaction.

At least one i) of the front wheel or wheels and ii) rear wheels 703and/or 704 is configured to drive band 402 along the band'scircumference if the band is a loop, or along the band's length if theband is a strip, and at a controllable drive velocity. Each drive wheelis connected to a controllable motor configured to drive a drive wheelin well-known fashion. In some embodiments of the present invention, thedrive velocity of the band correlates to a relative velocity ofdeposition head 322 to surface 521. For example, if the band isconfigured to act as a roller, the drive velocity can be applied suchthat the band is driven forward to match the relative movement of thedeposition head as it travels over the surface. In some embodiments ofthe present invention, a set of front and rear wheels are operated insuch a way that the amount of tension that is present along the lowerportion of band 402 is controlled to a particular range or amount.

As those who are skilled in the art will appreciate after reading thisspecification, one or more of the wheels coming in contact with band 402can be connected to mounting points 501 or 504, either as part of anactuator (e.g., actuator 502, actuator 505, etc.) that is connected to amounting point or separate from any actuator.

As explained above, lower member 701 of actuator 505 is connected to, orotherwise in contact with, band 402. Lower member 701 is capable ofmovement in relation to upper member 702, as explained below. It will beclear to those skilled in the art how to make and use actuator 505 suchthat member 701 moves according to a predetermined motion in relation tomember 702 and based on a second control signal (e.g., from controller301 as described below, etc.). Furthermore, it will be clear to thoseskilled in the art how to make and use actuator 505 such that one orboth of wheels 703 and 704 are capable of driving band 402 in apredetermined direction (e.g., up, down, etc.) and based on a firstcontrol signal (e.g., from controller 301 as described below, etc.).

Band assembly 401 further comprises upper band roller 509, and springassembly 510, which are configured to accommodate any slack that is inthe upper part of band 402, wherein the slack is required in order toaccommodate the rotation or linear movement of band 402 by one or moreactuators.

In those embodiments of the present invention in which band 402 is aloop, a byproduct of changing the shape of band 402 beneath and betweenpoints of contact 503 and 506 is that the length of band that is aboveand between points 503 and 506 needs to accommodate what amounts to adeformation of the band. Accordingly, the distance along the portion ofband 402 that is above and between points of contact 503 and 506 isgreater than the distance along the portion of the band that is beneathand between points 503 and 506, in order to provide the necessary slackor play in the upper portion of band 402. In some embodiments of thepresent invention, the distance along the portion of band 402 that isabove and between points of contact 503 and 506 is at least twice thedistance along the portion of the band that is beneath and betweenpoints 503 and 506. As those who are skilled in the art will appreciateafter reading this specification, a different ratio of distance betweenupper portion and lower portion of band 402 can be used.

FIGS. 8 through 12 depict different positions of a lower portion of band402, depending on the type of movement imparted to the band by actuator505. Although only actuator 505 is depicted as moving and according toone type of movement at a time, actuator 502 can move as well andaccording to any of the movements depicted in the subsequent drawingsfor actuator 505. Furthermore, each actuator, or group of multipleactuators, can be configured to impart multiple types of concurrentmovement (compound motion), depending on whether multiple solenoidsand/or motors are present in each actuator. Because actuators 502 and505 are capable of movement and because band 402 is coupled to theactuators, it can be said each actuator is configured to change theshape of the band.

In the drawings that follow, scenarios are provided depicting rotationaround a vertical axis, linear longitudinal motion, linear lateralmotion, and linear vertical motion. As those who are skilled in the artwill appreciate after reading this specification, however, an actuatorcan be configured to impart other types of motion, including rotationaround other axes and linear motion along other axes than depicted.

FIGS. 8A and 8B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401, with actuators502 and 505 in their neutral positions. In some alternative embodimentsof the present invention, one or both actuators can a different neutralposition than depicted.

FIGS. 9A and 9B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401. As depicted inthese figures, actuator 505 is configured to change the shape of band402 by imparting a linear longitudinal motion along longitudinal axis901 at point of contact 506. This motion results in band 402 compressingor expanding, in relation to mounting point 504.

FIGS. 10A and 10B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401. As depicted inthese figures, actuator 505 is configured to change the shape of band402 by imparting a linear lateral motion along lateral axis 1001 atpoint of contact 506. This motion results in band 402 shifting left orright, in relation to mounting point 504. This motion also results, asdepicted in FIGS. 10A and 10B, in roller 508 achieving a yawing movementto the left in relation to deposition head 322's direction of travelalong surface 521. If deposition head 322 were instead turned as a wholeto achieve the yawing movement, rather than shifting the band asdepicted, this could introduce unwanted sliding of the roller and bandagainst filament 331, possibly resulting in breaking of filament fibers.The motion produced in the manner depicted in FIGS. 10A and 10B avoidsthe sliding and possible breaking of the fibers.

As can be seen in FIG. 10B in particular, band 402 shifts sideways(i.e., toward the right). Depending on how band 402 is connected tomember 701, member 701 might be required to rotate or swivel accordinglyas it moves laterally, in order to accommodate the band.

FIGS. 11A and 11B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401. As depicted inthese figures, actuator 505 is configured to change the shape of band402 by imparting a linear vertical motion along vertical axis 1101 atpoint of contact 506. This motion results in band 402 shifting up ordown, in relation to mounting point 504, exposing actuator struts 1102and 1103 in FIG. 11B that support member 701 with respect to member 702during the motion.

FIGS. 12A and 12B depict respective, orthographic front- andleft-side-views of a lower portion of band assembly 401. As depicted inthese figures, actuator 505 is configured to change the shape of band402 by imparting a rotational motion about rotational axis 1201 at pointof contact 506. This motion results in band 402 twisting to the left orto the right, in relation to mounting point 504. As also depicted,actuator 502 is configured to change the shape of band 402 by impartinga rotational motion about rotational axis 1202 at point of contact 503.This motion results in band 402 twisting to the left or to the right, inrelation to mounting point 501.

As depicted in FIG. 12A, actuators 502 and 505 are twisting band 402 inopposite directions with respect to each other's axis. As a result ofthis, roller 508 rolls clockwise as depicted in FIG. 9B, enabling band402 to conform a tilt of surface 521, for example. In some alternativeembodiments of the present invention, the concavity can be conformed toby a combination of both twisting the band, as depicted, and tiltingdeposition head 322, or by only tilting deposition head 322, as needed.

As described earlier, actuator 502 can be configured similarly toactuator 505, in regard to imparting one or more of the aforementionedtypes of mechanical motion to band 402 at point of contact 503.Furthermore, the types of mechanical motion imparted by actuators 502and 505 can be the same as each other or can be different from eachother. For example and without limitation, one of the actuators canimpart a rotational motion about a vertical axis and the other actuatorcan impart a rotational motion as well (e.g., in the same rotationaldirection, in the opposite rotational direction, etc.) or a linear(e.g., lateral, longitudinal, vertical, etc.) motion.

By imparting a predetermined mechanical motion the point of contact onband 402, an actuator is able to change the shape of the band in such away that the band conforms, at least at point of compaction 522, to atleast some concavities on surface 521. Depending on the mechanicalmotion being imparted, a desired motion can also be imparted to roller508 (e.g., yaw, roll, etc.). Each type of mechanical motion can beapplied in order to address a certain contour of the concavity, and eachcombination of mechanical motions being imparted by two or moreactuators can be applied to address a certain contour not necessaryaddressable by a single actuator imparting a single type of mechanicalmotion.

FIG. 13 depicts salient operations of method 1300 according to theillustrative embodiment, by which controller 301 performs variousfunctions related to controlling actuator 505. As those who are skilledin the art will appreciate after reading this specification, a similarmethod can be applied to controlling actuator 502 as well.

In regard to method 1300, it will be clear to those having ordinaryskill in the art, after reading the present disclosure, how to make anduse alternative embodiments of the disclosed methods in which therecited operations, sub-operations, and messages are differentlysequenced, grouped, or sub-divided—all within the scope of the presentinvention. It will be further clear to those skilled in the art, afterreading the present disclosure, how to make and use alternativeembodiments of the disclosed methods wherein some of the describedoperations, sub-operations, and messages are optional, are omitted, orare performed by other elements and/or systems than the illustrativedevices associated with the respective methods.

In accordance with operation 1301, and dependent on the computer model,controller 301 provides a control signal to actuator 505 to impart alinear longitudinal motion along longitudinal axis 901 at point ofcontact 506, as depicted in FIG. 9. Controller 301 previously receivedthe computer model of object 351 prior to the start of the depositionprocess. In some embodiments of the present invention, the computermodel is based on the object being manufactured from thermoplasticfilament. The computer model is representative of one or more portionsof one or more segments of filament 131 being used to manufacture object351.

In accordance with operation 1303, and dependent on the computer model,controller 301 provides a control signal to actuator 505 to impart alinear lateral motion along lateral axis 1001 at point of contact 506,as depicted in FIG. 10.

In accordance with operation 1305, and dependent on the computer model,controller 301 provides a control signal to actuator 505 to impart alinear vertical motion along vertical axis 1101 at point of contact 506,as depicted in FIG. 11.

In accordance with operation 1307, and dependent on a stored,mathematical computer model of object 351, controller 301 provides acontrol signal to actuator 505 to impart a rotational motion aboutrotational axis 1201 at point of contact 506, as depicted in FIG. 12.

In accordance with operation 1309, and dependent on the computer modeland/or one or criteria, controller 301 provides a control signal to themotor of the drive wheel of at least one of actuators 502 and 505. Thecontrol signal operates to cause the corresponding drive wheel toadvance band 402 along its length by a first distance. Operation 1309 isdescribed below and in regard to FIG. 14.

FIG. 14 depicts operation 1309 for advancing band 402 along its length.There can be various causes of controller 301 providing a control signalto advance band 402 along its length, in any combination thereof, asdescribed below.

In accordance with operation 1401, and dependent on the computer modelof object 351, controller 301 provides the control signal in operation1309 based on thermoplastic build-up on a portion of band 402 thatoverlaps point of compaction 522. In some embodiments, the controlsignal is provided based on an estimate of thermoplastic build-up on theportion of band 402. Controller 301 advances the band sufficiently sothat a fresh portion of band surface is exposed and then used fordeposition and compaction. The advancement of band 402 can occurperiodically, continuously, sporadically, and so on.

In accordance with operation 1403, and dependent on the computer modelof object 351, controller 301 provides the control signal in operation1309 based on the fatigue limit of material that constitutes band 402.For example and without limitation, a material with a relatively lowfatigue limit might require more frequent advancements of band 402,while a material with a relatively high fatigue limit might require lessfrequent advancements of band 402, or none at all.

In accordance with operation 1405, and dependent on the computer modelof object 351, controller 301 provides the control signal in operation1309 dependent on one or more of the following, in any combination:

-   -   i. the number of times a control signal in operation 1301 has        been provided to actuator 502 and/or 505,    -   ii. the number of times a control signal in operation 1303 has        been provided to actuator 502 and/or 505,    -   iii. the number of times a control signal in operation 1305 has        been provided to actuator 502 and/or 505, and    -   iv. the number of times a control signal in operation 1307 has        been provided to actuator and/or 505.

In accordance with operation 1407, and dependent on the computer modelof object 351, controller 301 provides the control signal in operation1309 based on the type of mechanical motion (e.g., rotational, linearlongitudinal, linear lateral, linear vertical, etc.) that at least oneof actuator 502 and/or 505 imparts to band 402, or the type ofmechanical motion imparted to roller 508 (e.g., yaw left, yaw right,roll left, roll right, etc.), or both.

In accordance with operation 1409, and dependent on the computer modelof object 351, controller 301 provides a control signal in operation1309 to advance band 402 in a particular direction that is based on oneor more criteria. For example and without limitation, the control signalfrom controller 301 can cause band 402 to be advanced in a directionopposite to that in which filament drive 409 feeds filament 331 to pointof compaction 522, in response to thermoplastic build-up on the portionof band 402 exceeding a predetermined estimated value. As anotherexample, during the deposition of a filament segment, the control signalfrom controller 301 can cause band 402 to be advanced along the samedirection in which filament drive 409 feeds filament 331 to point ofcompaction 522, in those variations of the illustrative embodiment inwhich band 402 acts as a band roller in depositing filament 331.

In those variations of the illustrative embodiment in which band 402 isconfigured as a strip, instead of as a loop, the strip can be maintainedon two spools that are part of band assembly 401 (i.e., a front and rearspool), as already described. In this configuration, controller 301rewinds strip 402 (i.e., in the rewind direction) before the strip getsto its end. In order to facilitate this, controller 301 provides acontrol signal in operation 1309 based on i) if the band strip isconfigured to act as a compaction roller, the length(s) of one or morefilament segments already deposited or about to be deposited ontosurface 521, or ii) the estimated length of band strip remaining beforeit gets to its end, or both.

It is to be understood that the above-described embodiments are merelyillustrative of the present invention and that many variations of theabove-described embodiments can be devised by those skilled in the artwithout departing from the scope of the invention. It is thereforeintended that such variations be included within the scope of thefollowing claims and their equivalents.

What is claimed is:
 1. A deposition head for pressing a filament at apoint of compaction on a surface of an article of manufacture, thedeposition head comprising: a filament drive that is configured to feedthe filament toward the point of compaction; a heat source that isconfigured to heat the filament as it passes through an area between thefilament drive and the point of compaction; a body having a frontmounting point and a rear mounting point that are arranged along alongitudinal axis; a first actuator that is connected to the rearmounting point; and a band made of a flexible material, and having afirst connecting point that is connected to the front mounting point anda second connecting point that is connected to the rear mounting pointthrough the first actuator, such that an intermediate portion of theband between the first connecting point and second connecting point iscurved toward the surface of the article; wherein the first actuator isconfigured to impart a mechanical motion at the second connecting pointof the band, in relation to the rear mounting point, such that the bandconforms, at the point of compaction, to at least some concavities inthe surface of the article.
 2. The deposition head of claim 1 whereinthe first actuator is configured to impart a rotational motion about avertical axis at the second connecting point of the band, in relation tothe rear mounting point.
 3. The deposition head of claim 1 wherein thefirst actuator is configured to impart a linear longitudinal motion atthe second connecting point of the band, in relation to the rearmounting point.
 4. The deposition head of claim 1 wherein the firstactuator is configured to impart a linear lateral motion at the secondconnecting point of the band, in relation to the rear mounting point. 5.The deposition head of claim 1 wherein the first actuator is configuredto impart a linear vertical motion at the second connecting point of theband, in relation to the rear mounting point.
 6. The deposition head ofclaim 1, further comprising a second actuator that is connected to thefront mounting point, wherein the second actuator is configured toimpart a mechanical motion at the first connecting point of the band, inrelation to the front mounting point.
 7. The deposition head of claim 1,further comprising a compaction support extending from the body towardan inward-facing surface of the band, and configured to support the bandat the point of compaction.
 8. A deposition head for pressing a filamentat a point of compaction on a surface of an article of manufacture, thedeposition head comprising: a body having a front mounting point and arear mounting point arranged along a longitudinal axis; a first actuatorthat is connected to the body at one of the front mounting point and therear mounting point, a band made of a flexible material, and having afirst connecting point that is connected to the front mounting point anda second connecting point that is connected to the rear mounting point,wherein one of the first connecting point and second connecting point isconnected to the respective front or rear mounting point through thefirst actuator, such that an intermediate portion of the band betweenthe first connecting point and second connecting point is curved towardthe surface of the article; and a first compaction support extendingfrom the body toward an inward-facing surface of the band, andconfigured to support the band at the point of compaction; wherein thefirst actuator is configured to impart a first mechanical motion to oneof the first connecting point and the second connecting point of theband, in relation to the body.
 9. The deposition head of claim 8,further comprising a second actuator that is connected to the body atone of the front mounting point and the rear mounting point, wherein thesecond actuator is configured to impart a second mechanical motion toone of the first connecting point and the second connecting point of theband, in relation to the body.
 10. The deposition head of claim 9wherein the first mechanical motion is rotational motion about avertical axis at the second connecting point of the band, and whereinthe second mechanical motion is rotational motion about a vertical axisat the first connecting point of the band.
 11. The deposition head ofclaim 9 wherein the first mechanical motion is rotational motion about avertical axis at the second connecting point of the band, and whereinthe second mechanical motion is linear lateral motion at the secondconnecting point of the band.
 12. The deposition head of claim 9 whereinthe first mechanical motion is rotational motion about a vertical axisat the second connecting point of the band, and wherein the secondmechanical motion is linear longitudinal motion at the second connectingpoint of the band.
 13. The deposition head of claim 9 wherein the firstmechanical motion is rotational motion about a vertical axis at thesecond connecting point of the band, and wherein the second mechanicalmotion is linear vertical motion at the second connecting point of theband.
 14. The deposition head of claim 9 wherein the first mechanicalmotion is linear lateral motion at the second connecting point of theband, and wherein the second mechanical motion is linear vertical motionat the second connecting point of the band.
 15. The deposition head ofclaim 9 wherein the first mechanical motion is linear lateral motion atthe second connecting point of the band, and wherein the secondmechanical motion is linear longitudinal motion at the second connectingpoint of the band.
 16. The deposition head of claim 8, furthercomprising a second compaction support extending from the body towardthe inward-facing surface of the band.
 17. A deposition head forpressing a filament at a point of compaction on a surface of an articleof manufacture, the deposition head comprising: a body having a frontmounting point and a rear mounting point arranged along a longitudinalaxis; a first actuator that is connected to the body at one of the frontmounting point and the rear mounting point, a second actuator that isconnected to the body at one of the front mounting point and the rearmounting point, and a band made of a flexible material, and having afirst connecting point that is connected to the front mounting point anda second connecting point that is connected to the rear mounting point,wherein one of the first connecting point and second connecting point isconnected to the respective front or rear mounting point through thefirst actuator, such that an intermediate portion of the band betweenthe first connecting point and second connecting point is curved towardthe surface of the article; wherein the first actuator is configured toimpart a first mechanical motion to one of the first connecting pointand the second connecting point of the band, in relation to the body;and wherein the second actuator is configured to impart a secondmechanical motion to one of the first connecting point and the secondconnecting point of the band, in relation to the body.
 18. Thedeposition head of claim 17 wherein the first actuator is configured toimpart the first mechanical motion at the first connecting point of theband, and wherein the second actuator is configured to impart the secondmechanical motion at the first connecting point of the band.
 19. Thedeposition head of claim 17 wherein the first actuator is configured toimpart the first mechanical motion at the first connecting point of theband, and wherein the second actuator is configured to impart the secondmechanical motion at the second connecting point of the band.
 20. Thedeposition head of claim 17 wherein the first actuator is configured toimpart the first mechanical motion at the second connecting point of theband, and wherein the second actuator is configured to impart the secondmechanical motion at the second connecting point of the band.